Production of resilient filaments and fibers



April 17, 1945. R. B. HICKEY 2,373,892

' PRODUCTION OF RESILIENT FILAMENTS AND FIBERS I Filed Dec. :0, 1942 L0140 //v GRAMS 1. v ROBERT fi g gggy o v .2 .4 .6-8 10 n2 14/.6 /.e w/W0 DEPRESSION IN CMS. v BY 9 d v ATTyEYS Patented Apr. .1945

PRODUCTION OF RESILIENT FILAMENTS AND FIBERS Robert B. Hickey,Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey Application December 30,1942, Serial No.470,606

\ 3 Claims.

This invention relates to the preparation of resilient filaments andfibers composed of or containing organic derivatives of cellulose suchas cellulose acetate or other single or mixed cellulose organicacidesters, and more particularly to the preparation of filaments andfibers having a characteristic cross-section and especially adapted foruse in the manufacture of carpet materials and of rugging and other pilefabrics.

As is well known, in the manufacture of pile fabrics, particularly thoseof the coarser varieties such as carpeting, rugs and the like, thematter of resiliency and durability of the fibers employed is ofcritical importance. Most natural wools employed in the manufacture ofsuch fabrics are of the coarser, stronger and more resilient types.Carpet materials and rugging are generally of the pile type ofconstruction and it is highly important that the fibers employed in suchfabrics have a high crush resistance, that is, they must possess theability to return readily to their original positions in the fabricafter having been bent, displaced or distorted by application of aweight or other deforming force, such a is'the case when one walks on acarpet or rug.

Heretofore, many different types of filaments and fibers useful in theproduction of pile fabrics have been referred to in the prior art.Likewise,

'a large number of different fiber cross sections have-been referred to.However, so far as I am aware, no synthetic filament or-fiber has provedto be wholly satisfactory for use as a' substitute for natural carpetwool, such synthetic fibers not possessing the required degree of crushresistance or resiliency to enable them to be successfully used in suchpile fabrics as carpets and rugging.

The present invention has as its principal object to provide a processfor producing filaments and fibers having a high degree of crushresistance and resiliency. A further object is to provide a process forproducing filaments and fibers having properties which especially adaptthem for use in pile fabrics, either when used alone or in admixturewith other natural or synthetic filaments and fibers. A still furtherobject is to 'provide a process of producing'filaments and fibers of acharacteristic cross section. Other objects will appear hereinafter.

These objects are accomplished by the following invention which, in itsbroader aspects, is based upon the discovery that filaments or fibershaving a high degree of resiliency and crush resistance when used inpile fabrics must have a cross section corresponding to the crosssection of an I-beam and that such I-beam cross section filaments canbe" produced only by extruding a filament-forming solution through aspinneret having rectangular orifices, the ratio of the length to thewidth of which lies within certain specific numerical limits.Specifically, I have found that only by employing rectangular spinneretorifices in which this ratio of length to width lies between 1.35 and1.65 can such I-beam type cross section filaments and fibers beproduced. In other words I have found that this particular range ,ofratios is critical in the production of crush- .resistant filaments andfibers of the type herein set forth.

In the following examples and description, I have set forth several ofthe preferred embodiments of my invention, but they are included merelyfor purposes of illustration and not as a limitation thereof.

My invention will be more readily understood by reference to theaccompanying drawing in which,

Fig. 1 is a cross-sectional view, on a greatly magnified scale, of agroup of filaments produced in accordance with the instant invention.

Fig. 2 is a cross-sectional view illustrating the theoretical form of anI-beam type filament,

Fig. 3 is a graphical representation of the resiliency characteristicsof filaments produced in accordance withmy, invention as compared bothto natural wool and to filaments produced in accordance with prior artpractice.

Fig. 4 is an elevational view, partly in section,

illustrating one form of device for measuring resiliency.

Fig. 5 is a fragmentary plan view, greatly magnified, illustrating thegeneral rectangular contour of the spinning orifices employed inaccordwith myinvention, a typical example of such apparatus and spinningconditions being set forth in'the U. S. patents to Stone 2,000,047'and2,000,-

048. While my process is, as indicated above, fundamentally concernedwith extrusion of the spinning solution "through a spinneret, theorifices of which are characterized by the fact that their ratio oflength to width falls within a certain critical range, it will of coursebe understood altered, not only by the specific spinningconditionsemployed, as is well known, but also by the type of cellulose acetat orother cellulose ester it may be desired to use in making up the spinningsolution. For example, although not in any way limited thereto, I preferto employ the spinning solutions and spinning conditions described andclaimed in my U. S. Patent No. 2,338,641.

As stated, the distinguishing feature of my invention is the discovery,wholly contrary to what might be expected from a consideration of theprior art, that in order to obtain filaments having a true I-beam crosssection, as distinguished from a mere fiat or flattened cross-section,it is necessary to employ a rectangular spinning orifice in which theratio of length to'width lies within the critical range of 1.35 to 1.65.I have found that if one goes appreciably beyond this ratio orappreciably below it, the desired and highly characteristic I-beamcross-section is not obtained, notwithstanding many loose references toobtaining such filaments found in the prior art.

The highly characteristic and distinguishing features of filamentsproduced in accordance with my invention is that the cross-section ofsuch filaments is very definitely of the I-beam type. The

resiliency of such filaments compared to fila-' ments of rounded ormerely flattened cross-section produced in accordance with the-techniqueof the prior art will now be discussed, both from the standpoint of thetheoretical mechanics involved, and from the more practical standpointof crush resistance as measured by a somewhat empirical test.

The mechanical characteristics of different types of filaments may beshown by a consideration, respectively, of the three theoretical crosssections, namely, (A) circular, (B) oblong, and (I) beam. On the basisof mechanics the theoretical 'moment of inertia, modulus of elasticity.-

stiflness; relative stiffness and bending moment readily be calculated.employing the values of the different dimensions given on the drawing.These data are listed in the following tabulation:

Moment of inertia, mm. 2.72Xl- .26 10- 5.67 10- Modulus of elasticity, XX

kgJlnrn. 272 325 328 Stiffness, k g./mm.' 7.4)(10- 158x10" 18.6X10 Relatve stiffness l 092 2.51 Bending moment-to produce bend of 100 mm.

kg./mm 7.4)(- .68X10- 18.6)(10- It will be readily observed that afilament of I- beam cross section produces a much stiffer fiber which,in all. probability, accounts for the considerable improvement inresiliency and crush reslstance observed when such filaments areemployed in various fabric constructions, particu- -larly pile fabricsof the rug and carpet varieties.

weight or applied load being indicated by adiustment-of rider weight I.Positioned within .of filaments of the respective cross sections may a YType material Acetate staple Acetate staple.

' that the ultimate properties of the yarn may be and freely movable incylinder I is piston or presser 5 which is lowered or raised in thecylinder by means of loading screw 6 threadedly engaging collar 1 whichis rotatably mounted in bracket 8 which in turn is fixedly mounted onringstand 9. Pointer, I0 is fixedly mounted to the end of loading screw6 and is 50 positioned as to read along scale I I which is fixedlymounted with respect to ring stand 9.

. A load is applied to the fiber massby rotating collar 1 in such manneras to depress the'piston 5. The load, when the beam 3 is in a horizontalposition is read from scale S. The distance in centimeters the fibersare depressed by increasing the load and the amount they expand as theload is removed as indicated by travel of 'pointer l0 on scale H is anapproximate measure of their resiliency. In other words, the less theyare depressed by a given load and the more they recover when the load isremoved, the more resilient and crush resistance the fibers are said tobe. I

The results obtained when applying this test, respectively, to the 20denier per filament cellulose acetate staple fibers having the so-calledstandardclover leaf or round cross section, to cellulose acetate stapleof the same denier having an I-beam cross section and produced inaccordance with my invention, and to natural wool of approximately thesame fiber size, are indicated in the graphs of Fig. 3, in which graph Windicates the results obtained with natural wool, graph A with celluloseacetate fibers of cloverleaf or round'cross section and graph C withcellulose acetate fibers of I-beai'n cross section, all under the sameload.

It will be seen from these curves that the ability to return afterdepression is approximately the same for natural wool and for celluloseacetate fibers of -I- beam cross-section produced. in accordance with myinvention. Contrasted tothe resiliency and crush resistance of suchfibers is the rounded-cross-section fiber-of curve A in which theability to return to its original position after depression is markedlyless.

As a further and even more practical test of the comparative quality ofI-beam cross section filaments produced'in accordance with my processand standard rounded cross section filaments of the same denier, carpetswere made up from each type of staple fiber produced from suchfilaments. In evaluating such a carpet; several testswere run todetermine wear, resistance to abrasion, luxuriousness (or resistance toor recovery from compression) and resistance to soil. Tabulated beloware comparative results obtained in the test. a

Shape of cross-section Clover-leaf I-beam.

Shawmut wear test. Not as good as wool Asgoodaswool. Resistance toabrasion Very good. Luxury index (wool=l00%). 75% 93%.

. Resistance to soiling l Poor Good.

It will be readily seen from a consideration of the results obtained inthe various tests described above that'an I-beam cross section materialis superior in every respect to material composed I of filaments orfibers of the standard rounded or .I-beam cross-section having a highdegree '01 ties above described be produced. It will thus be seen that Ihave provided a valuable improvement in the dry spinning art in whichfilaments having especially valuable properties, such as -neret havingrectangular extrusion orifices in which the ratio of orifice length towidth is between 1.35 and 1.65 and coagulating the filaments byconducting them through a current oi heated evaporative medium.

2. The process of producing filaments oi truiresiliency and crushresistance and adapted'ior the manufacture of pile fabrics whichcomprises extruding a filament-forming solution composed of a celluloseorganic acid ester dissolved in a volatile solvent in the form offilaments through a spinneret having rectangular extrusion orifices inwhich'the ratio of orifice length to width is between 1.35 and 1.65 andcoagulating the filaments by conducting them through a current of heatedevaporative medium.

'3. The process of roducing filaments of true I-beam cross-sectionhaving a high degree of resiliency and crush resistance'and adapted forthe manufacture of pile fabrics which comprises extruding afilament-forming solution composed of cellulose acetate dissolved inacetone in the form of filaments-through a spinneret having rectangularextrusion orifices in which the ratio of orifice length to width isbetween 1.35 and 1.65 and coagulating the filaments by conductin themthrough a current of heated air.

ROBERT B. HICKEY.

